Menvier Fire

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T e c h n i c a l - F i r e S y s t e m D

e s i g n G u i d e

FIRE SYSTEM DESIGN GUIDE

SYSTEM DESIGN

In order to undertake the process of designing a fire system fora building it is necessary to have a sound understanding of therelevant design standards, the legal framework surroundingbuilding safety legislation and a sound working knowledge ofproduct application theory. The importance of consultation with allrelevant parties cannot be overstressed, neither can the importanceof specialist advice in relevant areas. The following system designprocess is intended to give a reasonable overview of all the areasof knowledge required for the successful design of a fire alarmsystem.

It is envisaged that the user will refer to the information containedwithin the design section to determine the areas where furtherdetailed advice will be required and to give guidance as to wheresuch advice may be contained.

Due to the complex nature of legislation and design standardsrelating to fire alarm system design, this design guide is notintended to be a comprehensive guide to all aspects of fire alarmdesign but rather a very useful source of background informationto which further application specific detailed information can beadded from other sources as required.

The standards referred to in this section relate to the UK andEurope. Although the principles are broadly universal, it isrecommended for readers in other countries that they familiarisethemselves with specific local requirements from their ownstandards, only using the British or European standards wherethese have been accepted by local fire authorities. Informationrelating to equipment facilities and performance apply to Cooper

Lighting and Security equipment and may not necessarily apply toother manufacturers equipment. The reader should carefully check whether such comments relate to equipment from othermanufacturers before considering alternative equipment.

OVERVIEW OF THE DESIGN PROCESS

The following describes a typical fire alarm system design process,after each item a section number is provided which relates to thearea within the design guide where further information can befound.• Understand the reasons for installing the fire alarm system in the

specific property (section 1)• Conduct a risk assessment to help determine requirements

(section 2)

• Consult with all interested parties (section 3)• Decide on the relevant design standard (section 4)• Establish if third party approval is required - for equipment and

/or installation.• Decide on the type of alarm technology to be used

(see pages 18-23)• Decide on the appropriate protection category and extent of

coverage where relevant (section 5)• Discuss and agree the fire strategy (section 6)• Plan the zoning of the building (section 6)• Select and position relevant system components (section 7)

- Select the appropriate detectors for each area- Position the detectors- Select suitable callpoints and position at appropriate

locations- Agree on the means of summoning the fire authority- Plan the alarm signalling arrangements (sounders, beacons,

pagers etc)

OVERVIEW OF THE DESIGN PROCESS (cont’d)

• Select a suitable panel (suitably sized and rated withadequate standby autonomy)

- Review the design such as to - minimise the potential for falsealarms (section 8)

- Select Contractor- Ensure suitable wiring of the system (section 9)- Make suitable arrangements for commissioning (section 10)- Appoint/Establish responsible person (section 11)- Make suitable arrangements for ongoing maintenance and

monitoring of system performance (section 11)

BACKGROUND LEGISLATION

The following section contains details of European legislation whichrelates mainly to legal requirements placed on the manufacturer orimporter of equipment. The description is included here to give theuser/specifier an understanding of the subject.

EMC

The EMC directive requires that all electrical and electronicequipment is able to co-exist without interference. There are twobasic levels, which relate to the type of environment, industrialand commercial/light industrial. The industrial level allowsequipment to emit more electrical noise taking into account theproblem of containing electrical noise in large electrical machines.EMC standards are continually evolving as communicationequipment becomes more sophisticated and measurementtechniques improve.

In principle Fire Alarm equipment must emit low levels of noise but

be able to withstand high levels, so that it can be used in allapplications. To that end a product family standard, EN50130-4has been published to cover alarm equipment susceptibility and thecommercial/light industrial generic standard is used for emissions.

LVD

The Low Voltage Directive requires that all electrical equipmentconnected to low voltage supplies (up to 1000V) must be safe.Various standards are published relating to different types ofequipment but the general standard EN60950 is applied to firedetection and alarm equipment.

Most items in commercial fire detection systems are designed towork at Extra Low Voltage (24V) and so the LVD does not apply,

the exceptions being fire alarm panels, mains rated relays orinterfaces and other items of equipment connected to the mainssupply such as door closers, smoke vents etc.

CPD

The Construction Products Directive relates to building materialsand equipment fixed to the structure of the building. One sectionof the directive relates to Safety In Case Of Fire and mandate109 requires that all fire detection and alarm equipment isthird party certified to the relevant Harmonised European standard.In most cases this will be a part of the EN54 suite of standards,e.g. EN54-2 for control equipment or EN54-5 for heat detectors.Many of these standards are published but are in the process ofharmonisation. Once harmonised there will be a transition period

before compliance becomes mandatory. Therefore at present thirdparty approval is voluntary but over the next few years it isexpected to become mandatory.


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CPD (cont’d)

Third party testing to an EN54 standard is very expensive,this may therefore restrict the level of customisation that can be

offered by manufacturers in the future.

CE MARKING

Currently CE marking is used to indicate that the equipment meetsthe EMC and LV directives. It will also apply to CPD complianceonce mandated standards are in place for the items of equipmentin question. CE marking is not retrospective and generally it will beclear as to what directive the marking relates to. The mandatedstandards will be parts of EN54 for fire alarm and fire detectionsystems.

RoHS

The Restriction of Hazardous Substances directive currently does

not apply to fire detection and alarm equipment. However it islikely that once alternative materials become available and reliable(particularly in the case of lead solder,) then the scope of thedirective will be enlarged to cover current exceptions and toincorporate more materials. The objective of the directive is torequire manufacturers to stop using substances that potentiallyprovide some health risk, in electrical and electronic equipment.

1.0 WHY HAVE A FIRE ALARM SYSTEM?

The answer to this question depends on the premises in questionand the legal requirements. In large high-rise buildings, suchsystems are essential to warn all occupants that a fire oremergency situation exists and the system is used to controlevacuation in an orderly way. Large sites with a retained fire

brigade may require the system to call the brigade and direct themto the area of risk. The property may have considerable intrinsicvalue and the insurers either require a fire detection system or mayincentivise its use.The building may be unoccupied for periods where equipment isstill powered and the owner wishes to ensure that if anything goeswrong fire fighters are called to the scene in a timely manner.Fire alarm systems are often used for other purposes as well as firedetection and alarm, such as bomb alert signalling, monitoringsystems for high risk equipment or places, emergency call systemsand even class change systems for schools.

Sometimes fire detection and alarm systems are used tocompensate for structural fire protection shortcomings or to give

special cover for items of high value. Whatever the reason,an automatic fire detection and alarm system generally providesa network of manual callpoints, fire sensors and alarm warningdevices over the area covered. It is, in effect, the eyes and mouthof the building to constantly monitor the building and warn if a firebreaks out, or is suspected. In the same way we do if we seeflames or smell burning.

1.1 Insurance Requirements

Insurance requirements normally relate to the protection of property- rather than life. The objective is therefore to detect fire as early aspossible and instigate measures to put the fire out with theminimum amount of damage.

Generally a system designed for property protection will also giveprotection of life as well but the essential difference is that therequirements for property protection are driven from the insurancecompany’s desires rather than law. BS5839-1 covers both life andproperty protection, so is equally useful in both cases.

1.2 Legal Framework

Generally the legal requirement for a fire alarm system relatesto the protection of life. Either of those in the building or thosein adjacent buildings. The primary objective of life protection isto warn occupants of the risk of fire and get them to a place ofsafety as quickly as possible.

The UK has traditionally had a number of regulations relating todifferent types of building and has used the fire brigade to act asa local enforcement agency either issuing or withholding firecertificates depending on their view of the level of protectionprovided. This is now changing and the government is devolvingthe responsibility onto the building owners - with some exceptions.This means that it will become the building owner (or occupier)who is responsible to ensure that the building is safe for those inand around it. The recommended tool to establish the requirementis ‘risk assessment’. The overall legal framework as it currently is

and is expected to become are detailed in the charts below.

Acts of Parliament

Government Departments

Fire Authority & Building Control

Implement Legislation, they inspectpremises and decide upon requirements

then issue Fire Certificates to premisesthat comply and are responsible for thefire safest standards of the building

Employer

Uses contractor to install products tomeet fire authority requirements who

will then issue a fire certificate

British Standards Institute

Produces standards of best engineeringpractice by consultation with allparties. They are called up in guidancedocuments as showing legal compliance

Enforced by courts

e.g. Home office, provide guidance

Fire Safety B ill - Act of Par liament Government Departments

Employers

and their

Fire Risk assessors

They have the total responsibility for the Fire safety of the premises

Enforced by courts e.g. Home office, provide guidance

Fire Authority & Building Control

Implement Legislation check assessments

Competent Engineers

Specialists in fire alarm and emergency

lighting design installation andmaintenance provide technical assistance

British Standards Institute

Produces standards for equipment andapplication that can be used by employersto demonstrate compliance

If a fire detection or alarm system is required then it isnecessary to establish the specification for the system. In theUK BS5839-1:2002 is normally the appropriate standard forcommercial and industrial premises. BS5839-6 relates toresidential premises and other standards such as HTM 82 forhospitals relate to specific building types.

FIRE SAFETY LEGISLATION - Current Situation

Flowchart of Fire Safety as expected for normal premisesafter Spring 2005


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2.0 RISK ASSESSMENT

The first step in the design process is the risk assessment.It underpins the whole system strategy and therefore could beargued as being the most important stage. Risk assessment is theprocess of considering each part of a building from the point ofview of what fire hazards exist within an area and what wouldhappen in the event of fire or if explosion were to occur. Thiswould normally be done when considering the building from thepoint of view of general safety. Clearly very small premises onlyrequire a first level of fire protection, such as safe construction,clear escape routes and a fire extinguisher. Equally obviously,large hotels will require a fully automatic fire detection and alarmsystem, multiple sets fire protection equipment and adequateemergency lighting and escape signage. The Risk Assessmentprocess is to help building owners of buildings between these twoextremes make adequate and appropriate provision.

Building owners or operators will often want to employ the servicesof a professional risk assessor to ensure that the buildingis considered impartially and in adequate detail. However thereare checklists and technical advice available so that the task canbe done ‘in-house’. The web site of the office of the deputyPrime Minister provides useful guidance on the subject(www.odpm.gov.uk). Additional information and guidance on therisk assessment process is available from the Health and Safetyexecutive (www.hse.gov.uk). It is recommended that risk assessorsshould be fully familiar with the requirements of BS5839:1 2002and if in doubt consult a suitably qualified specialist.

3.0 CONSULT WITH ALL INTERESTED PARTIES

BS5839 stresses the need to consult with all interested partiesbefore embarking on a detailed design. As a minimum thefollowing need to consult to ensure that the fire detection andalarm system meets the requirements of all concerned.- The authority responsible for enforcing health and safety

legislation- The property insurer- The building user- The proposed installer- Fire engineering specialists (where appropriate)

4.0 RELEVANT STANDARDS

Standards are produced for equipment and the application ofequipment, they are generally produced or endorsed by BSI.They represent recognised best practice either for the design,manufacture or application of a particular product or productrange.

Often these standards are called up within guidance documentsfor pieces of legislation and since they represent best currentpractice, can be generally be used by employers to demonstratethat equipment they have installed is adequate and appropriate.The following standards relate to the UK and Europe. There areother standards that relate to specific applications (such ashospitals or data processing installations) and other countries willhave their own standards covering the same area as those listed.

4.1 BS5839

The BS5839 suite of standards relate to specific areas ofapplication for fire detection and alarm equipment. Specificallypart 1 relates to public premises and part 6 relates to residentialpremises.

4.1 BS5839 (cont’d)

BS5839-1 is a comprehensive code of practice for fire detectionand alarm systems, the requirements relate to both life and property

protection and the standard includes much advice and commentwith is very useful in informing the building owner or systemspecifier of the background to the requirements. The standard hasbeen developed through input from the whole fire detectionindustry over a period of 30 years and is the distillation of expertopinion and practical advice. The application notes that followrelate to the requirements of BS5839:1 2002.

4.2 BS5588

The parts of BS5588 form the technical element of the buildingregulations for England and Wales, they should be consulted toestablish the detailed requirements for the building in question.BS5588 is mainly concerned with the structure and design of the

building but also contains some requirements for fire detection andalarm systems. The requirements of BS5588 are incorporatedwithin the building regulations giving it mandatory legal status.

4.3 BS7273, BS EN 60079-14, BS EN 50281-1-2

The parts of BS7273 are codes of practice for different types offire protection systems. Generally this is considered separately tofire alarm systems but there may be occasions where a trade offcan be made between the two systems, or where the two systemsinteract and must be interfaced.

BS EN 60079-14 and 50281-1-2 cover areas where there maybe risk of explosive gas/vapour or dust respectively, reference tothem may be required in certain buildings or where there is a

change of use.

4.4 EN54

The EN54 suite of standards relates to the design andperformance of items of equipment that make up a fire detectionand alarm system. Each part relates to a different piece ofequipment, for example part 3 relates to alarm devices, part 11 tocall points, part 4 to power supplies etc.

Some parts of the standards have options with requirements. Theserelate to specific features that are required in certain applicationsbut not all. For example all control and indicating equipment mustbe able to detect fire (with the help of appropriate input devices),must monitor certain functions (such as cables for open and short

circuit faults) and must have a disablement facility so that functionsor areas of cover can be switched off for maintenance or similaractivities. However it is optional to have a test facility or delays tooutputs, but if such features are either provided or required in theapplication (e.g. to allow a local search for fire prior to calling thebrigade) then those facilities must meet specified criteria.

It is therefore necessary when specifying compliance to EN54 thatthe relevant part is identified and that the application standard(such as BS5839-1) is consulted to identify specific options. Forexample, the UK fire brigade almost always will require zonal lightemitting indicators to be incorporated in control equipment to showthe extent of the fire event at a glance; this is an option in EN54-2and many countries in Europe do not require such displays.

4.5 BS7671

BS7671 was previously known as the IEE wiring regulations.The standard is called up in BS5839-1 and covers the installationof the system.


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5.0 SELECTION OF COVER

BS5839-1 lists eight categories of cover, depending on what isrequired. The category system is a simple short hand method ofinforming all parties of the objective of the system.

5.1 Life Safety

M - Category M systems are manual systems and rely on theoccupants of the building discovering the fire and acting towarn others by operating the system. Such systems form thebasic requirement for places of employment with nosleeping risk. Manual cover should be included in all LifeSafety systems except L5 systems where it may or may not

be provided. In addition to manual means of triggering analarm, L category systems will also normally have anelement of coverage using automatic fire detection such assmoke or heat detectors. The precise classification dependson the nature of the area(s) provided with automaticprotection

L5 - Category 5 systems are the ‘custom’ category and relate tosome special requirement that cannot be covered by anyother category. Where such systems are specified carefulreference much be made to the objective of the cover.

L4 - Category 4 systems cover escape routes and circulationareas only. Detectors might be sited in other areas of thebuilding, but the objective is to protect the escape route.

L3 - Category 3 systems provide more extensive cover thancategory 4. The objective is to warn the occupants of thebuilding early enough to ensure that all are able to exit thebuilding before escape routes become impassable.

L2 - Category 2 systems relate to automatic fire protection indefined areas of the building as well as satisfying the

requirements of category 3. The wider cover would relate toparts of the building considered to have a high level of risk.

L1 - With category 1 systems, the whole of a building iscovered apart from minor exceptions.

5.2 Property Protection

P2 - Category 2 systems provide fire detection in specified partsof the building where there is either high risk or wherebusiness disruption must be minimised.

P1 - The system is installed throughout the building - the objectivebeing to call the fire brigade as early as possible to ensurethat any damage caused by fire is minimised. Small low risk areas can be excepted, such as toilets and cupboards lessthan 1m2.

6.0 REVIEW OF THE BUILDING

Before looking at the details of the alarm system it is necessary tounderstand some of the concepts that are used to assist the systemdesigner. Buildings are divided up into sections in three ways asfar as fire safety engineering is concerned; fire compartments,detection zones and alarm zones.

6.1 Fire Compartments

A fire compartment is a part of a building that is separated fromthe rest of the building by a fire resistant structure so as to limit thespread of fire within the building. The requirements for designing abuilding and hence its fire compartments, are defined in building

regulations and is outside the scope of this document. It isnecessary, however, for the designer of a fire detection and alarmsystem to be familiar with the design of the building, in particularthe position and extent of its fire compartments.

6.2 Detection Zones

Fire detection zones are essentially a convenient way of dividingup a building to assist in quickly locating the position of a fire.The zone boundaries are not physical features of the building,although it is normal to make the zone boundary coincide withwalls, floors and specifically fire compartments. The size andposition of the detection zones will therefore tend to be dependanton the shape of the buildings, but will also depend on what thebuilding is used for and to some extent the number of people thebuilding is expected to contain at any one time.BS 5839-1 has some specific recommendations with respect todetection zones:- Zones should be restricted to single floors, except where the

total floor area of a building is less than 300m2

- Voids above or below the floor area of a room may beincluded in the same zone as the room so long as they areboth in the same fire compartment

- Zones should not be larger than 2000m2 except for manualsystems in single storey open plan buildings, such as awarehouse, where up to 10000m2 is allowed

- Fire detectors in an enclosed stairwell, lift shaft or the likeshould be considered as a separate zone

- The search distance within a zone should be less than 60m(all possible entrance points must be considered). This can berelaxed when using addressable systems if the informationprovided at the control and indicating equipment would allowfire fighters, unfamiliar with the building, to proceed directly tothe location of the fire. The search distance only relates to thedistance from entering a zone to being able to determine thelocation of the fire, it is not necessary to travel to the fire

- Zones should not cross fire compartments, a fire compartment

can contain several zones but a zone should not contain morethan one fire compartment

S e a r c h d i s t a n c e


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6.3 Alarm Zones

Alarm zones are only needed in buildings where operation of thealarms needs to be different in certain parts of the buildings. If theonly requirement is to activate all the alarm sounders to provide asingle common evacuate signal once a fire is detected, then alarmzones are not needed, the whole building is one alarm zone.For more complex buildings where it is necessary to operate alarmdevices differently in parts of the building, then the building shouldbe divided into alarm zones such that all of the alarm devices inone alarm zone operate in the same way.BS5839-1 contains some recommendations for alarm zones:- The boundaries of all alarm zones should comprise fire-resisting

construction- Signal overlap between alarm zones should not cause

confusion- The same alarm and alert signals should be used throughout a

building

- A detection zone must not contain multiple alarm zones, alarmand detection zone boundaries should coincide. An alarm zonemay contain multiple detection zones

7.0 SELECTION OF EQUIPMENT

7.1 Component Compatibility

Because most conventional systems operate in a similar manner,there can be a temptation to mix and match detectors, panels andsounders from different suppliers. Cooper Lighting and Securitystrongly recommend that all components be sourced from a singlesupplier to ensure that they are fully compatible with each other.Minor incompatibilities between components may not beimmediately obvious but could cause system malfunction under

particular conditions.

Section 11.1 of BS5839 part 1:2002 makes specific mention ofthe need to confirm that all system components are fully compatiblewith each other.

Note also that section 12.2.2 of BS5839 part 1:2002 requiresthat removal of any or all detectors from a circuit should not affectthe operation of any manual callpoint. With Cooper Lighting andSecurity conventional systems, this functionality is inherentlyprovided by the design of the detector base, however with othersystems this requirement may require the purchase of additionalcomponents or place limitations on the wiring order of detectorsand callpoints. Other countries may require that this requirement

is met by the use of separate zones (e.g. France).

7.2 Repeater Panels

Repeater panels are available for most systems and are requiredwhere the fire brigade may enter a building from more than oneentrance, where security staff are located away from the mainpanel or where operational staff need the system information inmore than one location, for example in hospital wards.

All control panels including most repeaters, require two powersupplies. The back up supply is built into the panel and is providedby sealed lead acid batteries, but a secure mains supply isrequired for the primary power source. Fuses/isolation switchesshould be clearly marked to ensure that the fire alarm system is

not inadvertently powered down.

7.3 Selection of Suitable Equipment Autonomy

Standby time for life safety systems is normally 24 hrs. For propertyprotection this may need to be increased to up to 72hrs where thebuilding is unoccupied over weekends.

Conventional panels and most repeater panels generally havebatteries, which are sized to provide a defined level of standbyautonomy based on a fully loaded system. For analogue systems,batteries are typically custom sized to suit the requiredconfiguration, because the amount and type of connectedequipment can vary considerably.

7.4 Selection of Appropriate Automatic Detectors

Cooper Lighting and Security provide a range of automatic firedetectors to suit most general risks. Smoke detectors give theearliest warning of fire, typically responding to a fire 1/10thof the size as that required to operate a heat detector.

Optical smoke detectors are suitable for most applications givingthe fastest response to slow burning fires - the most common startto fire events. Ionisation detectors were the first type of detector tobe commercially developed and are also a popular choice.They have superior response to fast burning fires but an inferiorresponse to slow smouldering fires, which are typical with modernconstruction materials. Ionisation detectors are also less acceptablefrom an environmental point of view due to the radioactive materialthat they contain. There is increasing restriction on thetransportation and disposal of ionisation detectors so it isrecommended that alternative types are used where possible.

BS5839 section 21.1.8 (d) recommends the use of opticaldetectors to provide coverage for escape routes due to theirsuperior ability to detect optically dense smoke that would easilyobstruct the use of escape routes.

Opto-heat detectors have been developed to mimic the responseof ionisation detectors to fast burning clean fires yet maintain theadvantage of photoelectric detectors when detecting smoulderingfires and allow a higher alarm threshold within the EN54-7specification under normal conditions thus providing a greaterrejection of false alarms.

Heat detectors should be used in environments where the ambientconditions might cause false alarms if smoke detection were to beused, for example where there is a high level of dust, fumes, steam

or smoke under normal conditions.

There are three available types of conventional heat detector,a fixed high temperature heat detector which has a nominal triggertemperature of 92°C, a medium fixed temperature heat detectorwith a nominal trigger threshold of 77°C and a rate of rise heatdetector which responds to the rate of change in temperaturerather than at a specific temperature. Rate of rise detectors alsohave a fixed temperature backstop to ensure that even very slowincreases in temperature will eventually raise an alarm if theincrease continues for a sufficiently long period.

The rate of rise type is the most sensitive type of heat detector,particularly when used in areas where the ambient temperature

can reach low levels and therefore create a large differencebetween the ambient temperature and the trigger temperatureof a fixed temperature detector.


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7.4 Selection of Appropriate Automatic Detectors (cont’d)

In order to avoid false alarms rate of rise detectors should not beused in areas subject to frequent temperature swings, such as in

kitchens, boiler rooms and warehouses with large doors to openair. BS5839-1 recommends that the static response temperature ofa heat detector should be a minimum of 29°C above themaximum ambient temperature likely to be experienced for longperiods of time and 4°C above the maximum temperature likelyto be experienced for short periods of time.

Each type of conventional heat detector is manufactured to havespecific characteristics, which cannot be altered. Becauseanalogue systems are more sophisticated, only a single analogueheat detector is produced, the characteristic of which isprogrammable to suit the relevant application requirements at thetime of commissioning and can be altered later if required.

Heat detectors must be mounted closer together than smokedetectors, so whilst the mounting bases are compatible for alltypes, care should be taken to ensure that the spacing betweendetectors is appropriate for the detector type fitted. With analoguesystems it is possible for the photo thermal detector to act as athermally enhanced smoke detector during certain times and asa pure heat detector at other times. If this mode of operation isenvisaged then spacings must be those appropriate for heatdetectors.

7.5 Positioning of Smoke and Heat Detectors

All smoke detectors have similar spacing requirements, heatdetectors also all have similar spacing requirements although theseare different to smoke detectors. According to BS5839 for generalareas the spacing between any point in a protected area and thedetector nearest to that point should not exceed 7.5m for a smokedetector and 5.3m for a heat detector.

The above are the maximum areas that can be covered by anindividual detector. In order to ensure that coverage is providedinto the corners of rooms and to ensure that there is no gap at thejunction point of multiple detectors, spacings have to be reduced.

To ensure complete coverage for square layouts, spacings between

detectors and walls should be reduced to 5m for a smoke detectorand 3.5m for a heat detector.

Area of coverage fora smoke detector

Area of coverage fora heat detector

= Missed coverage in the corners of rooms and intersections

7 . 5 M m

a x

7.5M max 5.3M max

5 . 3 M m

a x

7 . 5 M m

a x

5 . 3 M m

a x 5M

5M

3.5M

3.5M


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7.5 Positioning of Smoke and Heat Detectors (cont’d)

To ensure complete coverage, spacings between detectors shouldbe reduced to 10.0m between smoke detectors and 7.0m

between heat detectors.

For corridors less than 2m wide only the centre line need beconsidered therefore it is not necessary to reduce detector spacingsin order to provide complete coverage. Therefore for smokedetectors spacing becomes 7.5m from a wall and 15.0m betweendetectors. For heat detectors the spacing becomes 5.3m to a walland 10.6m between detectors.

The above data is based on flat level ceilings; for pitched ceilingsor ceilings with a non-flat surface, spacings will alter. For pitchedceilings use the data below, for other ceiling types refer toBS5839 for comprehensive guidance. Where detectors must be

mounted onto a pitched ceiling, a detector should be mountednear to the apex but spacing can be increased by 1% for each1° of slope up to 25%. ‘Near’ is defined as within 600mm forsmoke detectors and within 150mm for heat detectors.

7.6 Mounting Heights of Detectors

Under all normal circumstances point type fire detectors should bemounted on the ceiling - this ensures that the height restrictions aremet together with the following table.

Spacings between smokedetectors

Corridor spacing for smoke detectors

Spacings between heatdetectors

Ceiling Heights (m)

General Limits Rapid Attendance*

Heat detectors - class A1 9 13.5

Heat detectors - other classes 7.5 12

Point type smoke detectors 10.5 15

Optical beam smoke detectors 25 40

* Rapid attendance values can be used in type P systems providing fire brigaderesponse time is less than 5 minutes

10M

10M

7.5M MAX 7.5M MAX 7.5M MAX

15M

7M

25°

5 M

5 M

5 M

5 M

5 M + 2 5 %

5 M + 2 5 %

5 M + 2 5 %

7M


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7.7 Beams and Other Similar Ceiling Obstructions

Fire detectors should be mounted at least 500mm away from wallsor ceiling obstructions greater than 250mm deep and at leasttwice the depth of obstructions less than 250mm deep. Theyshould also be mounted at least 1m away from any forced airinlet. Where the obstruction is greater than 10% of the height of anarea it should be considered as a wall. Similarly a floor mountedobstruction (such as racking) should be considered a wall if itcomes to within 300mm of the height of the detector.

7.8 Lift Shafts

Where detection is required in vertical shafts, such as stairwells,a detector should be mounted at the top of the shaft and within1.5m at each level.

Typical detector positioning for L2 coverage

For obstructions of less than 250mm Y should be atleast 2 x Z

Detector at top of shaft

Detectorswithin 1.5m of penetration of

each floor

1.5m

Z

Y

1.5m

1.5m


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7.9 Beam Detectors

Beam detectors provide a cost effective method of covering wideopen plan areas, however care should be taken that activities inthe space do not obstruct the beam and that the building structureis such that the beam does not ‘move’ or false operation mayresult.

If optical beam detectors are mounted within 600mm of the ceilinglevel, they should be positioned such that no point in a protectedspace is more than 7.5m from the nearest part of the opticalbeam. Should the beam detector be mounted more than 600mmbelow ceiling level then spacings should be altered to 12.5% ofthe height of the beam detector above the highest likely seat ofany fire.

Other than the part of the beam within 500mm of the beam’stransmitter or receiver, if any other section of a beam which runs

closer than 500mm to any wall partition or other obstruction to theflow of hot gasses, that section of the beam should be discountedfrom providing protection.

Where optical beam detectors are mounted in the apex of pitchedroofs then the same enhanced spacings can be applied as forpoint smoke detectors (see above)

The area covered by a single optical beam detector should notexceed that of a single detection zone.

7.10 Aspirating Systems

Aspirating systems should be specified where protection is requiredin areas such as cold stores or areas where a very fast response tofire is needed, and whilst each sense point can be considereda smoke detector, special training is needed to design suchsystems - particularly as they are normally required to cover specialrisks. Other specialist detectors can be connected to CooperLighting and Security systems via interfaces where there is aspecific requirement, such as flame detectors or equipment in areasrequiring an intrinsically safe installation.

7.11 Selection of Manual Callpoints

The selection of manual call points is somewhat simpler. Surfaceor flush types are selected depending on the environment andwhether the fire system is being installed into an existing building(where surface call points are generally easier to install). IP65types should be specified where there is risk of moisture ingress,for example in external locations. Standard call points use afrangible glass element which is designed to break under lightpressure triggering the call point into an alarm condition.

The glass element is covered with a thick plastic film to protect theoperator against broken glass, however plastic resettable elementsand protective flaps can be used where there is the risk ofunwanted operation or in food preparation areas. Where hingedcovers are used these should be recorded as a design variation.Call points can be supplied with LED indicators mounted onto thefront face to simplify the location of an operated call point.


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The method of operation of call points should be the samethroughout the building - all Cooper Lighting and Security callpoints meet this requirement, whether IP65 or standard types.

7.12 Positioning of Manual Callpoints

Manual call points should be located on escape routes, at all exitsto free air and at all exits from each level of multi-storey buildings.

For general applications, call points should be located such thatnobody need to travel more than 45m to reach the nearest callpoint. This distance is based on measuring the actual route thatwould be travelled. If at the design stage the actual layout isunknown then a straight-line distance of 30m should be used as adesign guide and the 45m limit verified after fit out is complete.

Call points should be located near to specific hazards(e.g. flammable liquid store) and at 1.4m (+/- 0.2m) from the floorin well lit easily accessible positions. Lower mounting heights mightbe needed to accommodate building users in wheel chairs.

The figures of 45m and 30m above should be reduced to 25m

and 16m respectively if either a significant proportion of buildingusers have limited mobility and it can reasonably be assumed thatone of these occupants will be likely to be the first person tooperate the alarm or if the nature of equipment or activity in anarea gives a high likelihood of rapid fire development.

Typical building layout showing positioning of callpoints Typical building layout showing positioning of callpoints


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7.13 Remote indicators

Remote indicators should be used in areas where the detectormounting position is such that the detector is not easily viewed,for example in ceiling voids. Remote indicators can also be usedto dramatically reduce search distances where detectors aremounted inside rooms, such as in hotels, thus simplifying systemzoning and reducing the time taken to locate the source of analarm.

Without remote indication With remote indication

ZoneEntry

Search Path

ZoneEntry

Search Path


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0

5

54321 109876 11 12 13 14 15 16 17 18 19 20

10

15

20

25

30

Distance from Source

R e d u c t i o n

i n

D B

( A )

Distance from Reduction in

Source (m) DB(A)

1 0

2 6

3 9.2

4 12

5 13.96 15.5

7 16.9

8 18

9 19

10 20

11 20.8

12 21.5

13 22.2

14 22.9

15 23.5

16 24

17 24.6

18 25.1

19 25.5

20 26

Effect of distance on sound level

7.14 Alarm Devices

Alarm devices fall into two types, audible and visual. The audibletypes are most common, with a variety of types being availablefrom bells to all kinds of different electronic sounders includingthose containing pre-recorded spoken messages. The choice ofdevice is dependant on local preference, legal requirement andthe need to have a tone distinct from all other building audiblealarms.

Speech alarms or links to PA systems overcome some of thecomplacent responses to warning tones and can be used to goodeffect when carrying out regular fire tests in buildings where thereare many people unfamiliar with the regular routines - such ashotels. Finally visual alarms are to be used where the hard ofhearing may be occupying a building or where the ambient noiseis such (above 90dBA) that audible warning may not be heard,where hearing protectors are in use or where the sounder levels

would need to be so high that they might impair the hearing of thebuilding occupant.

BS5839-1 requires that Alarm Circuits should be arranged suchthat in the event of a single fault at least one sounder operateswithin the vicinity of the control equipment; or in the case of certainbuildings open to large numbers of the general public, a singlefault only partially reduces the alarm level. This is met by loop-powered devices or by the use of multiple alarm lines forconventional systems, interleaved throughout the relevant area orby use of at least two zones for Bi wire systems (single zoneBi wire panels have a built-in sounder incorporated within thecontrol panel).

Sound levels should generally be 65dBA or 5dBA above persistentbackground noise levels. This may be reduced to 60dBA in roomssmaller than 60m2, in stairwells or in specific limited points of thebuilding. Most sounders have adjustable output levels, whichallows a balance between meeting the requirements of thestandard and providing a sensible level of audible comfort.

Generally more low output sounders are better than few highoutput sounders in this respect.

In addition to these general requirements the following specificrequirements should also be noted:- A level of at least 75dBA at the bedhead is required to wake

sleeping occupants- At least one sounder is required per fire compartment- All of the sounders utilised in a building should emit a similar

noise

When considering the number and position of sounders thefollowing should be considered:- A loss of at least 20 to 30dBA should be allowed for sound

going through doors- Where two identical sounders are in one location the level

increases by only 3dBA- The sound pressure level drops with distance according to the

graph below- It is necessary to consider cable loading requirements when

designing sounder circuits. Volt drop should be limited to lessthan 10% of nominal voltage

- It is recommended to always err on the side of caution whenselecting sounders and their locations as it is far simpler toreduce the volume setting of a sounder where appropriatethan to retrofit additional sounders should the initial levels beinadequate

Sounder output levels are normally quoted in dB(a) at 1m,the graph below can be used to calculate effect on sound level

at other distances in free air. In addition allowances have to bemade for obstructions such as doors, the absorption of sound byfurnishings the directional nature of the sounder, mounting positionand location of the sounder etc.


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7.15 Fire Protection Equipment

Cooper Lighting and Security provide a range of door holders,interfaces and relays that can be used to control the operationof smoke vents, hatches, ventilation systems, lifts etc. It isrecommended that reference is made to the individual productpages of this catalogue or to our technical sales department whowill be able to advise on the best type for a particular application.

7.16 Alarm Routing Equipment

Alarm output relays are available to connect to alarm routingequipment. The selection of types of routing equipment will dependon the requirements of the selected alarm receiving centre.

7.17 Interfaces

The product pages of this catalogue list the range of interfaces thatare available, most relate to analogue systems and are designed

for specific applications, such as interfacing an analogue panel toa conventional zone of detectors, providing an interface to a shopetc. Conventional systems can interface directly to volt free contactsby using suitable resistors (for monitoring sprinkler flow switches forexample) and are provided with relay outputs in the panels toconnect to fire and fault routing equipment, fire protectionequipment etc.

By definition an interface bridges the gap between two piecesof equipment or two systems, consequently it is essential toconsider the requirements of both sides of the interface both from aloading point of view and with regard to functionality and typicalfault scenarios.

The main area of caution is to ensure that the voltage rating of theequipment and interface are compatible. For example, 24V relaycontacts should not be used to switch mains voltage, even if theyappear to work and it is best to provide isolation between systems(such as protection and alarm systems) so that there is no risk ofelectrical interference causing false alarms.

Typical sounder positioning based on sounder with 105dB(a)

Typical sounder positioning based on sounder with 105dB(a)


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Photo thermal detectors analyse both change in temperature aswell as density of smoke or smoke like phenomena. This canconsiderably reduce the potential for false alarms. In addition withanalogue systems it is possible to configure the detector to operatein heat only mode at specific times when smoke or smoke likephenomena is likely to be present and then to revert to combinedsmoke and heat detection when the presence of smoke is nolonger expected.

9.0 CABLES

BS5839-1:2002 introduced more onerous requirements forthe types of cables used in fire detection and alarm systems.Fireproof cables should now be used for all parts of the systemand enhanced fire resistance cables should be used where there isa requirement to ensure cable integrity over a longer period oftime. For example when connecting to alarm sounders or wherethe connection between sub-panels provides any part of the alarmsignal path.

Fire alarm cables should be segregated from the cables of othersystems; they should be clearly marked, preferably coloured redand should be routed through parts of the building that provideminimum risk. This latter point is particularly relevant where theuse of the building is being changed - for example if a fuel storeis being moved.

10.0 MAINTENANCE

Regular testing and inspection of the fire alarm system is essentialto ensure that it is operating correctly. Many of the functions of thesystem are monitored but it will still require an inspection of thepanel by the responsible person to see the fault indication and allsuch events should be entered into the system log together with theimplementation of an action plan to investigate the reason for thefault and a repair/correction program.

The Cooper Lighting and Security service division is able toprovide this function. The advantage of making use of this facilityis that the service department will have ready access to all sparesand to information relating to possible design changes orspecification enhancements that invariably happen over time.

BS5839-1 recommends the following minimum regular tests andinspections:Daily - Check to see if the system is indicating fault and that anycorrective actions have taken place.Weekly - Test the system by operating a manual call point (differentone each week).Periodic Inspection - Subject to risk assessment, should not exceed6 months between visits. Check the system log and ensure thatcorrective actions have taken place. Visually inspect all items ofequipment, to ensure that the system is not obstructed or renderedinappropriate by change of use. Check for any false alarms,compare to nationally accepted levels and take appropriate actionif unacceptable. Test the system on standby power to ensure thatthe battery is functioning correctly. Check all outputs for correct

operation. Check all controls and indicators. Check remotesignalling equipment. Additionally any other special checks - forexample beam detectors for correct alignment.Over 12 month period - Carried out over 2 or more visits.In addition to the periodic inspection: Test all manual call pointsand fire detectors for correct operation. Inspect the analoguedetector levels to ensure that they are within correct levels.Check all alarm devices for correct operation. Visually inspect allaccessible cable fixings. Confirm the cause and effectprogramming is correct and up to date.

11.0 SYSTEM EXTENSIONS

An extension to a fire alarm system should be planned andimplemented with the same care and consideration that was given

to the original system. There is always a risk that small extensionsmay affect the integrity of the whole system. Special care isneeded if a different manufacturer is chosen for the extension toensure that there is compatibility between the old and newequipment and to ensure that system loading constraints are met.

Area

Kitchens Smoke detectors should never be used

Avoid rate of rise heat detectorsAreas close to kitchens Avoid smoke detectors if possible

Do not install Ionisation smoke detectorsConsider photo thermal detector

Rooms in which toasters are used Avoid smoke detectors if possibleDo not install ionisation smoke detectors

Consider photo thermal detectorRooms in which people smoke Avoid smoke detectors i f possible

Do not install optical smoke detectorsConsider photo thermal detector

Bathrooms shower rooms and areas Avoid smoke detectors if possiblewhere steam occurs Do not install optical smoke detectors

Consider photo thermal detector

Areas with high dust concentrations Avoid smoke detectors if possibleDo not install optical smoke detectorsConsider photo thermal detector

Areas where the sensing element is Do not install ionisation smoke detectorssubject to high air velocity

Areas in which engine exhaust fumes Avoid smoke detectors if possibleoccur Do not install ionisation smoke detectors

Do not install beam detectorsConsider photo thermal detector

Areas close to openable windows Avoid smoke detectors if possibleDo not install ionisation smoke detectors

8.0 DESIGN REVIEW TO MINIMISE FALSE ALARM POTENTIAL

False alarms have the potential to cause substantial disruption tothe smooth running of a business and in addition place atremendous burden on fire service resources.Regular false alarms can cause building users to disregard alarmsignals leading to incorrect actions in the event of a real firesituation. False alarms can broadly be divided into four categories,- Unwanted alarms- Equipment false alarms- Malicious false alarms- False alarms with good intent

Unwanted alarms are those that are caused by a combination offactors such as environmental conditions, fire like phenomena suchas steam, aerosol spray or dust triggering smoke detectors or byinappropriate action by people in the building such as smoking inareas protected by smoke detectors.

The following is designed to assist with selection of equipment toavoid common potential unwanted alarm conditions, BS5839gives comprehensive guidance on the subject and should beconsulted for in depth guidance.


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T e c h n i c a l - I P R a t i n g s

IP RATINGS

Example: IP65 is dust tight and jet proof

The International Protection code, sometimes called the Ingress Protection code, classifies the protection given by an enclosure against thetouching of live parts, contact with moving parts and protection against the ingress of foreign solid bodies. It additionally specifies protectionagainst the harmful ingress of moisture or liquids. Two digits are used to describe its protection rating, called the IP code.

First Digit - Protection against solid objects Second Digit - Protection against liquids

No protection 0 No protection

Protection against large sized bodies e.g. hands 1 Protection against vertically falling drops of water

Protec tion against medium sized bodies e.g. fingers 2 Protec tion against drops of water up to 15° from the ver tical (Drip proof)

Protection against small bodies, 2.5mm dia. or greater e.g. tools, wires 3 Protection against rain falling up to 60° from the vertical (Rain proof)

Protect ion against very small bodies, 1mm dia. or greater 4 Protect ion against splashed water f rom any angle (Splash proof )

Protec tion against harmful deposi ts of dust (Dust proof) 5 Protect ion against jet s of water from any angle (Jet proof)

Complete protection agains t deposi ts of dust (Dus t t ight ) 6 Protect ion against water from heavy seas e.g. water t ight for marine deck use

7 Protected against immersion for a defined period

8 Protected against immersion for an indefinite period


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T e c h n i c a l - G l o s s a r y o f T e r m s

GLOSSARY OF TERMS

Addressable system is a system in which signals from detectors and callpoints are individually identified at the control panel and often where alarmdevices are individually addressed.

Alarm of fire is a warning of outbreak of fire, originated by a person or byan automatic device.

Alarm receiving centre is a permanently manned centre, usually provided bya commercial organisation, the staff of which, upon receipt of a fire signalnotify the fire service.

Analogue system A fire alarm system where the detectors give variableoutput signals representing the value of sensed phenomena.

Automatic fire alarm system is a fire alarm system comprising componentsfor automatically detecting a fire, initiating an alarm of fire and initiatingother action as arranged; the system may include manual call points.

Beam detector A type of smoke detector which detects smoke by theobscuration of a beam of infra red light passing between a transmitter andreceiver.

Conventional fire alarm Normally consists of a control panel linked to anumber of circuits of smoke, heat detectors and manual call points, andhaving a number of sounder circuits. Consists of a control panel providingseparate circuits per zone for detectors and call points and at least twocircuits for alarm devices.

Critical signal path All components and interconnections between every firealarm initiation point (callpoints and detectors) and every fire alarm device.

Fault warning is an automatic indication given audibly and/or visibly that afault exists in a fire alarm system.

Fire alarm control and indicating equipment is the hub of a fire alarm system,providing controls and normally a power supply for the system.

Fire alarm control equipment is equipment that, on receipt of a fire signal,controls the giving of a fire alarm by one or more of the following:(a) Fire alarm sounders(b) Fire alarm indicating equipment(c) Transmitting a signal to other fire alarm control equipment

Fire alarm device is a component of a fire alarm system used to givewarning of fire usually a sounder or visual alarm.

Fire alarm indicating equipment is the part of a fire alarm system located atprotected premises which provides indication of any fire alarm or faultwarning received from fire alarm control equipment.

Fire alarm remote indicating equipment is the part of an alarm system thatindicates the status of the protected premises from where a fire alarm or fault

warning is being transmitted.

Fire alarm sounder is a component of a fire alarm system for giving anaudible warning of fire.

Fire alarm system is a system of fixed apparatus for giving an audibleand/or visible and/or other perceptible alarm of fire and which may alsoinitiate other action. The term normally incorporates the function of firedetection as well as alarm.

Fire alarm transmission link is an electrical circuit for transmitting fire signalsand fault warnings from protected premises to a central (fire alarm) station orto a control room.

Fire Authority is the Local Government Authority with a statutory responsibilityfor providing the services of a fire brigade and supporting services in a

given geographical area.

Fire detection system is a system of fixed apparatus, normally part of anautomatic fire alarm system, in which fire detectors, control equipment andindicating equipment are employed for automatically detecting fire and

initiating other action as arranged.

Fire detector is a device which gives a signal in response to a change in theambient conditions in the vicinity or within range of the detector, due to afire.

Fire point is a location where fire-fighting equipment is positioned which mayalso comprise a fire alarm call point and fire instruction notices, the wholebeing provided and arranged for use by occupants of premises.

Fire procedure is collectively and individually all the actions that need to betaken, as part of fire precautions by the occupants of a building or otherstructure to ensure the avoidance of danger from fire to persons andproperty.

Fire protection is design features, systems or equipment in a building,structure or other fire risk, to reduce danger to persons and property bydetecting, extinguishing or containing fires.

Fire signal is an alarm of fire originated by an automatic device, givenaudibly and/or visibly.

Heat detector is a form of fire detector that responds to an increase intemperature.

Ionisation smoke detector is a smoke detector that responds when smoke,having entered the detector, causes a change in ionisation currents within thedetector.

Lantern Light A construction standing above the surface of a roof designedto provide light to the space below.

Manual fire alarm call point is a device for the manual instigation of a firealarm condition.

Manual fire alarm system is a fire alarm system without automatic detectors,in which the alarm system is initiated manually.

Mimic diagram is a topographic representation of the protected premisescarrying indicators for each sub division so that the indicators of the firealarm system can be rapidly related to the layout of the premises.

Phased evacuation System of evacuation in which different parts of thebuilding are evacuated in a controlled sequence rather than all at once.

Photoelectric smoke detector is a form of fire detector having a photoelectriccell which responds when light is absorbed or scattered by smoke particles.

Point fire detector is a form of fire detector which responds to the

phenomenon detected at a fixed point at its location.

Smoke detector is a form of fire detector that responds to particulateproducts of combustion.

Soft addressing allows the control panel to assign an address to eachdevice automatically instead of it being done manually.

Self learn mode allows a totally unprogrammed system to functionimmediately power and battery are connected (without the need for devicerelated text). The control panel will interrogate each device and assign anaddress (soft addressing). Manual zone allocation allows the installer to splitthe devices into zones.

Short circuit isolator Component in an addressable system that is able toisolate a detection loop at both sides of a short circuit, minimising the loss of

communication.

Documents

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